Revert "Revert "Merge pull request #10901 from armstrjare/fix_query_null_foreign_key_on_new_record_collection_ids_reader""

This reverts commit 5009b07887.

Also updated the CHANGELOG and adjusted the test-case to match the one on master.

activerecord/lib/active_record/associations/collection_association.rb

@@ -43,7 +43,7 @@ module ActiveRecord
 
       # Implements the ids reader method, e.g. foo.item_ids for Foo.has_many :items
       def ids_reader
-        if loaded? || options[:finder_sql]
+        if owner.new_record? || loaded? || options[:finder_sql]
           load_target.map do |record|
             record.send(reflection.association_primary_key)
           end